The purpose of this research study is to understand how breath is related to nutritional status. The procedures involved in this study include blood and breath sampling, questionnaires about health history, medications, nutritional status and diet, and a physical examination. Breath markers will be compared between individuals with and without malnutrition and be compared to indicators of malnutrition. Some individuals will undergo an interventional study involving 2 days of consuming study beverages and fasting along with providing additional breath samples to see if the breath changes in response to short-term changes in nutritional status.